1. Field of the Invention
The present invention relates to a camera having means for detecting the position of a gazing line.
2. Related Background Art
Hitherto, there has been developed a variety of cameras in each of which the value of photometry to be used for controlling the exposure, can be obtained variably.
For example, there has been a structure arranged, as shown in FIGS. 6A, 6B and 6C, in such a manner that three different photometry areas are provided (spot photometry subjected to the central portion, partial photometry subjected to the central portion and mean photometry subjected to the central portion with weighting), from which a preferable area can be selected. The above-described photometry methods respectively have the following characteristics so that a user is able to select a method which is suitable to take a photograph of the subject.
(a) Central spot photometry subjected to the central portion: only about 2.7% of the central portion of the image plane is subjected to the photometry, the subjected area being an area smaller than that subjected to the partial photometry for the central portion. In particular, only a small portion of the main subject is photographed according to the above-described method. Therefore, the above-described method can be suitably employed to take a stage photograph, a contact photograph and a closeup photograph.
(b) Partial photometry subjected to the central portion: only the main subject is subjected to the photometry. It is efficient to take a backlighted portrait or the like. Only 13% of the central portion is subjected to the photometry.
(c) Mean photometry subjected to the central portion with weighting: an ordinary photometry method which is suitably used for substantially all of the ordinary photographing and in which the brightness of the entire surface of the frame is measured. The photometry sensitivity distribution is characterized as designated by contour lines shown in FIG. 6C. Light at the central portion is sensed strongest and light intensity is damped toward the outside. According to this method, the influence from the sky can be prevented.
Furthermore, a so-called evaluation photometry has been disclosed.
However, with the conventional camera, the user must select any of the above-described three photometry methods. Therefore, it is difficult to select the most suitable photometry method depending upon the determination of the state of the subject, the state of the light direction and the like.
Furthermore, in order to handle the photometry mode selection button for the purpose of changing the photometry method, the user must not keep the eyes on the finder as usual. Therefore, the framing must be performed again.
As described above, since the selection of the photometry method necessitates an expert knowledge, it is a complicated work to change the photometry method. As a result, a user usually tends to use only one photometry method. Therefore, the advantage, in that there is provided a multiplicity of photometry methods, cannot be enjoyed.
Hitherto, there have been disclosed a variety of cameras of the type provided with a focal point exposure control function, that is, so-called a depth mode for setting the position of the focal point and the exposure value at the time of the photography by using both information about the position of the focal point and information about the photometry value of one or more points.
The depth mode is a mode with which the range (the depth of field) in which, for example, the focusing can be established, is able to be set as desired by a user. Then, the depth mode will be described with reference to FIG. 13. In the case where the subjects (A) to (C) disposed, as shown in FIG. 13A, at different distances from camera C are desired to be focused, the subject (A) is placed in the ranging frame of the camera C and a release button is depressed halfway (a switch SW.sub.1 is switched on). Then, the subject (C) is also placed in the ranging frame and the release button is similarly depressed halfway. As a result of the above-described operation, an M.P.U. (Micro-Processor Unit) in the camera stores information about the position of the focal point of each of the subjects (A) and (C). Furthermore, the position of the focal point between the nearest subject (A) and the farthest subject (C) with which an ideal width of the depth can be obtained is calculated. In addition, the aperture value with which the subjects (A) and (C) are placed in the depth of field is calculated. With the aperture value thus calculated, the shutter speed is obtained. In the case where only the subject (B) at the central portion is desired to be focused as shown in FIG. 13B, the subject (B) is placed in the ranging frame and the halfway depressing the release button is performed two times. As a result, a photograph having a reduced depth can be obtained in which only the subject (B) can be focused and the other subjects (A) and (C) become dim.
However, according to the above-described conventional structure, the point or the range which is desired to be focused must be set by the user by directing the ranging frame to the nearest point and the farthest point and the halfway depressing of the release button must be repeated two times. Therefore, the setting operation becomes too complicated for the user to be performed and takes too long a time.
Recently, the quantity of information to be inputted to recent cameras has been increased in accordance with the tendency of the cameras having a multi-function. With the conventional camera, a user operates the push button switch or a dial type switch so as to input information about, for example, the photometry and the range. In general, when the types of information are increased, the handling becomes too complicated.
There have been disclosed a variety of so-called multi-spot exposure control devices arranged in such a manner that a plurality of optional points on the surface to be observed (the surface to be focused), which are information necessary for the photographing, is subjected to photometry so as to obtain the photometry value of each of the plurality of points by a predetermined method so that the exposure is controlled by using the result of the calculation of the photometry value.
FIG. 20 is a schematic view which illustrates an essential portion of a camera having a conventional multispot exposure control device.
Referring to the drawing, the user selects a mode of spot-photometry for the central portion by a photometry mode selection button disposed in a camera grip portion. Then, the user aligns a spot photometry range mark disposed at the central portion of a finder (surface to be observed) with the region desired to be subjected to the photometry, and depresses a spot photometry button. Thus, the obtained spot photometry value is stored in storage so as to be used for controlling the exposure.
In the case where a plurality of points are desired to be subjected to the photometry in a weighted manner, the camera is moved so as to align the spot photometry range mark at the central portion of the finder with the plurality of subject regions, and the spot photometry button is successively depressed. Thus, for example, the weighted average values of the photometry values of the plurality of points are obtained whenever the spot photometry button is depressed, the weighted average values being then stored in storage. By using the weighted average value of the photometry values at the plurality of points thus stored, information about exposure necessary for the exposure control is obtained.
In the conventional multi-spot photometry device utilizing the photometry values at the plurality of points in the surface to be observed, the spot photometry can be performed in only one place at the central portion of the finder (surface to be observed). Therefore, the user must move the camera so as to align the spot photometry range mark with the subject region whenever an optional point is selected in the surface to be observed.
Therefore, the user must move the camera after determining the framing so as to obtain the photometry values at the plurality of points so as to store them in storage. Furthermore, the user must again move the camera to the original position. As a result, the user must perform too complicated a handling operation. That is, the framing must be again performed after the photometry operation and the camera must be moved whenever the above-described operation is performed. Furthermore, the camera with a tripod cannot be easily moved in general. Therefore, the multi-spot photometry function cannot be effectively enjoyed.